In a solution of potassium hydroxide weighing 120 g and a mass fraction of 6%, added 40 g of water

| August 14, 2021 | education

In a solution of potassium hydroxide weighing 120 g and a mass fraction of 6%, added 40 g of water. Determine the mass fraction of potassium hydroxide in the resulting solution.

1) Find the mass of the substance KOH, based on the formula W% = m substance: m solution * 100%.

m of the substance KOH = 120 g * 6%: 100% = 7.2 g.

2) Find the mass of the new solution. According to the condition, it was said that 40 grams of water was added. This means that the mass of the solution can now be expressed as follows – m of the new solution = 120 g + 40 g = 160 g.

3) Find the mass fraction of potassium hydroxide in the resulting solution. To do this, we will carry out calculations according to the same formula as in the first paragraph. The only thing that has changed for us is the mass of the solution. Therefore, W% KOH = 7.2 g: 160 g * 100% = 4.5%.

Answer: 4.5.



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